Currently, the installation of all smart meters is manually performed by workers in the field. In this case, smart meters are electronic watt-hour meters that are capable of checking the amounts of power used for each time period in real time and performing two-way communication with a power provider. Since smart meters are manually installed, there are many cases where normal connection is not achieved and a connection error occurs due to the carelessness of a worker, distraction attributable to the difficult environment of a site where a smart meter is located, or the like. In particular, a possibility that a connection error occurs in a three-phase four-wire smart meter installed for a customer who uses relatively higher power is much higher than a possibility that a connection error occurs in a single-phase two-wire smart meter.
Because of connection errors, “insufficient measurement,” “excessive measurement,” and “zero measurement” in which a measured value is zero occur. “Insufficient measurement” or “zero measurement” causes a serious loss from the point of view of a power provider, and “excessive measurement” causes a serious loss from the point of view of a customer.
To prevent such a connection error, a connection error has been detected using the phase values of voltage and current. However, to detect a connection error using phase values, there is inconvenience in which the zero crossing of voltage and current alternating current waveforms should be implemented.
Furthermore, in the case of a smart meter in which a analog block (an ADC converter) and a digital block (a DSP or an MCU) have been implemented in one chip, if separate zero crossing is not implemented, the phase difference between voltage and current is obtained using active and reactive energy values calculated for a specific period and then a connection error is determined. Accordingly, it is difficult to determine the time at which the phase difference used to determine a connection error is calculated, and thus a problem arises in that the accuracy of the determination of a connection error is low.